126 
ON  ALUMINIUM. 
Making  for  the  materials  for  manufacturing  one  pound  of 
aluminium,  estimated  at  the  market  prices,  5J  cents.  Practically 
it  requires — 
16  lbs.  of  the  double  chloride  of  aluminium  and 
sodium,  at  8  cts.  per  lb.,  $1  28 
2|  lbs.  metallic  sodium,  at  about  26  cents  per  lb.,  70 
Flux  and  cost  of  reduction,  2  02 
Total,  $4  00 
By  manufacturing  on  a  larger  scale,  and  by  using  the  slag  as 
a  flux  instead  of  employing  fresh  material,  the  lowest  cost  will  be 
reduced  to  the  following  : 
10  lbs.  of  double  chloride  of  aluminium  and  sodium, 
at  41  cts.  per  lb.,  $0  45 
21  lbs.  of  sodium,  at  14  cts.  per  lb.,  35 
Cost  of  reduction,  20 
Total,  $1  00 
It  is  seen  that  the  actual  cost  of  one  pound  of  aluminium,  when 
manufactured  extensively,  will  be  about  double  the  theoretical 
cost  as  before  estimated,  (fifty-one  cents.) 
For  the  production  of  aluminium  are  used  clay,  salts,  sulphur, 
manganese,  lime  and  fluor  spar,  materials  which  are  very  abun- 
dant and  cheap  ;  all  that  is  now  required  is  practical  experience, 
to  reduce  the  price  of  the  metal  still  nearer  to  the  price  of  the 
raw  materials,  as  has  been  before  stated.  The  history  of  the 
useful  arts  contains  numerous  instances  that,  where  skill  and 
perfection  of  apparatus  are  required,  difficulties  are  speedily 
overcome. 
The  density  of  aluminium  when  moulded  is  2-56.  The  density 
of  aluminium  when  rolled  is  2-67.  In  equal  weight  with  silver 
it  is  four  times  more  voluminous.  In  equal  weights  with  copper, 
bronze,  bass  and  German  silver,  it  possesses  from  three  to  three 
and  a  half  times  greater  volume.  In  equal  volumes  with  the 
above  metals  and  alloys  it  possesses  greater  rigidity. 
Mention  has  already  been  made  of  a  very  important  property 
of  aluminium  when  pure  j  that  is  to  resist  oxidation,  a  property 
which  it  possesses  to  a  greater  degree  than  the  other  metals. 
Aluminium  is  not  acted  upon  by  nitric  acid,  hydrosulphuric 
